1. Field of the Invention
The present invention relates to a substrate processing apparatus and a substrate processing method.
2. Description of the Related Art
Recently, an etching target film of a substrate, such as a wafer or the like for a semiconductor device, is being multi-layered. Generally, an etching target film is formed of a photoresist film, a reflection preventing film, a hard mask, an oxide film, or the like, and it is required to etch each of etching target films by using one substrate processing apparatus from a point of view for production efficiency improvement despite different etching conditions of each film, i.e., to etch each etching target film by using one substrate processing apparatus while changing an etching condition.
In order to change an etching condition in one substrate processing apparatus, not only is a type of a process gas supplied into a process chamber accommodating a substrate or a value of high frequency power applied to an inside of the process chamber required to be changed, but also a pressure inside the process chamber is required to be adjusted. Conventionally, the pressure inside the process chamber is adjusted by an Adaptive Pressure Controller (hereinafter, referred to as an APC) provided at an exhaust pipe that evacuates a gas inside the process chamber, but since the APC adjusts the pressure by using a slide valve having a large diameter, it is difficult to precisely adjust the pressure in an almost opened state or an almost closed state, i.e., at a relatively low pressure or a relatively high pressure.
Thus, recently, precise adjustment of the pressure at a relatively low pressure or a relatively high pressure by adjusting a degree of easiness of a gas flow in the process chamber, specifically, the degree of easiness (exhaust conductance) of exhaust from the process chamber, is being studied. For example, adjusting a pressure on a wafer or confining plasma by arranging a plurality of rings each having a diameter larger than a wafer to surround the wafer in the process chamber and adjusting an interval between the rings has been suggested (for example, refer to Patent Reference 1).
However, in a technology of Patent Reference 1 described above, since the rings are arranged in the process chamber, reaction products may be attached to the rings, and thus particles may be appeared as the reaction products are peeled off when the rings move. Also, although the interval between the rings is adjustable, the rings cannot be removed, and thus exhaust resistance resulting from the arrangement of the rings cannot be removed. Accordingly, an adjustment range of the exhaust conductance is still limited. Further, since the rings are arranged inside the process chamber, distribution of plasma may be scattered.
3. Prior Art Reference
(Patent Reference 1) Japanese Unexamined Patent Application Publication (Translation of PCT application) No. 2008-527634